The present invention relates to a process of preparing sucroglycerides.
It is known that the expression "sucroglyceride" designates the mixture of products obtained by reaction of sucrose with natural or synthetic triglycerides, which mixture contains monoglycerides, diglycerides, unchanged triglycerides (in small amounts), monoesters and diesters of sucrose in variable proportions depending on the nature of the triglyceride used and the proportion thereof employed with respect to the sucrose. Thus it is possible for the sucrose to be combined in a form ranging from monoesters to octaesters.
The term "combined sucrose" is understood by those skilled in the art to mean sucrose in its esterified form. As used herein, the term "sucrose" is used synonymously with the term "saccharose" and is intended to include sugar whether from beet or cane sources.
The sucroglycerides have interesting emulsifying properties due, in particular, to the sucrose mono- and diesters and the monoglycerides. These nonionic emulsifiers are completely biodegradable, non-toxic, odorless, tasteless, and well tolerated by living organisms. Consequently, they are used in human and animal food-stuffs and in numerous other fields of use, such as for example, household or industrial detergents, cosmetics, etc.
The reaction of transesterification of the triglycerides and sucrose, leading to liberating alcohol functions of the glycerol, is an equilibrium reaction which is difficult to displace, as a result of the high boiling point of the glycerol and the fact that properties analogous to sucrose make separation difficult.
The result is that the product obtained depends on the chemical equilibrium present between the sucrose and the glycerol in the reaction phase, which equilibrium is related to the concentration of the substances in this phase. However, as sucrose and the triglycerides are practically insoluble in each other, the reaction appears theoretically impossible in the absence of a common solvent which permits a certain concentration of the reagents in the reaction phase or phases.
Common solvents are rare and the one most commonly used in dimethylformamide. Indeed, it has been proposed to carry out the transesterification of sucrose and natural triglycerides in dimethylformamide, in the presence of anhydrous potassium carbonate, the reaction temperature being about 95.degree. C. (See Italian Pat. No. 650,389). However, some traces of dimethylformamide or its derivatives always remain in the resultant sucroglycerides and these traces may be disturbing from a physiological viewpoint.
The use of other solvents has been recommended, such as pyridine, (U.S. Pat. No. 2,831,855), derivatives of morpholine or piperidine (U.S. Pat. No. 2,831,856) and dimethylsulfoxide (U.S. Pat. No. 2,812,324), but these solvents are scarcely any more satisfactory for use in foods.
More recently, research has been done on solventless processes which use either a fine dispersion of sucrose (Patent of Addition to French Pat. No. 2,029,508-69/15314), or a high temperature such as 190.degree. C. (French Pat. No. 2,047,603-70/17075), or very long reaction times of about 10 to 20 hours (French Patent No. 2,221,436-74/08639). These processes are characterized by the presence of large amounts of 20 to 25%, or even more, of emulsifying agents or their precursors (soaps or potassium carbonate which produces soaps). The product obtained at the end of the reaction is highly colored thus showing the decomposition of the sucrose and contains a large amount of soaps while having relatively little combined sucrose.
For use in foods, it is desirable not to have more than 6% soaps in the emulsifiers. Therefore, it is desirable to provide a method for the industrial production of sucroglycerides which contain a minimum amount of soaps, thus making possible an increase in weight yield since the presence of surplus amounts of soaps must be eliminated by costly purification methods.
A method of manufacturing sucroglycerides has now been found in accordance with the present invention, which, in its optimal form, leads to the obtaining of sucroglycerides suitable without further treatment for food use since non-toxic compounds are used and there is a formation of a minimal amount of soaps. Also, the operating conditions of the process are such they they lead to a low carmelization of the sucrose.
It is, accordingly, an object of the present invention to provide a novel and effective process for producing sucroglycerides which process eliminates many of the disadvantages of prior art processes.
It is a further object of the invention to provide a useful and effective process for producing sucroglycerides which can be used, without extended purification, in foods.
Other objects of the invention will be apparent to those skilled in the art from the present disclosure.